Automatic loading firearms having a breech block temporarily held in locked position by a sliding system



. 2,788,715 ORARILY HELD IN LDCKED POSITION BY A suomc svs'mu .April 16,1957 m i -r AUTOMATIC LOADING FIREARMS HAVING A BREECH BLOCK TEMP FiledFeb. 9, 1951 m A TTURNEY United States Patent AUTOMATIC LOADING FIREARMSHAVING A BREECH BLOCK TEMPORARILY HELD IN LOCKED POSITION BY A SLIDINGSYSTEM Marc Birkigt, Versoix, near Geneva, Switzerland, assignor toBrevets Aero-Mecaniques, S. A., Geneva, Switzerland, a society ofSwitzerland Application February 9, 1951, Serial No. 210,105 Claimspriority, application Luxemburg February 18, 1950 1 Claim. (Cl. 89-190)The present invention relates to automatic loading firearms (this termincluding, in the following specification and claim, semi-automaticfirearms the reloading of which takes place automatically but the firingof which is performed manually for every shot, fully automatic firearmsfiring by bursts and firearms capable of working eithersemi-automatically or automatically) in which the movable breechblock isheld temporarily locked in position by a movable system capable, oncethe breechblock has reached the end of its forward stroke, of slidingwith respect to said breechblock so as temporarily to prevent unlockingof the breechblock. And it is more especially concerned with automaticguns in which the sliding system is constituted by two longitudinalsliding bars disposed on either side of the breechblock inside thebreech casing.

It is of interest, in firerams of this kind, to provide safety meanscapable of preventing accidental rebounding of this sliding system,because such a rebounding might, it of sufficient amplitude, bring thesliding system into a position such that unlocking of the breechblockcould take place, which would be particularly dangerous if it occurredwhile the firing of the shot is being delayed for some reasons (hangfire).

It was already suggested, in my Patent No. 2,361,985, of November 7,1944, to constitute such safety means by providing in the sliding systemat least one housing in which was disposed a sliding mass capable ofassuming, when the system, at the end of its frontward stroke, came tostrike the breech casing, a displacement at the end of which it struckthe front end of its housing with a shock tending to oppose reboundingof the sliding system.

According to this prior solution, the sliding system was constituted bytwo slide bars interposed between the breech block and the breechcasing, each sliding bar containing a sliding mass wholly enclosed in ahousing open laterally both on the side of the breech casing and on thatof the breechblock. Furthermore, said sliding mass was subjected to theaction of imperative guiding means (in this case a plunger piston)carried by thecorresponding slide bar.

For practical purposes, the sliding mass was guided exclusively by thisplunger piston and there remained, be tween said mass and the breechcasing on the one hand and between said mass and the breechblock on theother hand, functional plays making it possible for the mass to slidefreely in its housing. In particular, possible transverse reactionsexerted on the slide bars in the course of the frontward movement of thebreechblock remained without influence upon the behaviour of the slidingmasses which remained normally applied against the rear end of theirhousing under the only actions of their return springs and inertiaforces.

It is highly desirable to cause the sliding masses to remain in thisrear position as long as the slide bars have not reached the end oftheir frontward stroke, since in this way the frontward relativemovement of said masses is then of maximum amplitude (the intensity ofthe com- 2,788,715 Patented Apr. 16, 1957 pensating shock varyingtogether with the amplitude of this movement).

The chief object of the present invention is to create supplementarysafety means for achieving a correct positioning of the sliding masswhen its frontward displacement is to start relatively to the slidingsystem, which safety means may be of capital importance if the slidingmass return spring fails to work (accidental breaking or weakening ofsaid return spring).

According to the present invention, the sliding mass and the arm breechcasing are made to cooperate frictionally so as to develop substantialfriction forces, advantageously by contact between the adjacent walls ofthese two elements, and at least during the end portion of the frontwardmovement of the sliding system, whereby the friction forces brought intoplay during this phase of the operation contribute in keeping thesliding mass in its rearmost position.

A preferred embodiment of the invention will be hereinafter describedwith reference to the accompanying drawings, given merely by way ofexample and in which:

Fig. 1 shows, in elevation and with parts cut away, the breech mechanismof an automatic firearm made according to the invention.

Fig. 2 is a cross section on the line 11-11 of Fig. 1.

Fig. 3 is a plan view of a locking control member included in saidbreech mechanism.

The firearm includes a tube 1 provided at the rear with a breech casing2 in which can slide, in a direction parallel to the firing axis, amovable breechblock 3 subjected to the action of a recuperator spring 4which urges it constantly toward the front and provided with lockingmember 5 adapted to bear against a surface 5;: carried by the breechcasing so as to hold the breechblock in its front position when a shotis being fired.

In order temporarily to keep locking member 5 in active position, Iprovide a sliding system constituted by two slide bars 6 disposed oneither side of breechblock 3, between said breechblock and breech casing2, and connected together by a striker holder 7 against which bearsrecuperator spring 4 and which extends through an elongated passage 8provided in the breechblock, whereby the sliding system can have, oncesaid breechblock has reached the end of its frontward stroke, asupplementary displacement which brings holding portions of slide bars 6on locking member 5 to keep it applied against surface 50.

Rearward movement of slide bars 6 after a shot has been fired isachieved by a gas tap control system the driving portion of which isshown on the drawing and which acts upon said slide bars through a fork9 and released accidentally.

push-piece 10.

With such a construction, slide bars 6 mightrebound toward the rear, atthe end of their frontward strokes, and thus make it possible for thebreechblock 3 to be In order to reduce these risks, I provide thesliding system, and preferably every slide bar 6, with at least onesliding mass or weight 11 capable of moving, in a direction parallel tothe movement of the slide bars and against the action of a return spring12, from a rearmost p0sition (in which it is applied against a rearabutment 13 rigid with the slide bar) to a front position (in which itstrikes a front abutment 14 also rigid with the slide bar).

During the frontward movement of slide bars 6, weights 11 are normallykept in rear position by the combined actions of their inertia andreturn springs 12. When the front edge 6a of said slide bars strikes therear edge of the firearm barrel 1, weights 11, driven by their inertia,keep moving froutwardly and strike the front ab-utments 14 of 'the'slidebars 6, thus preventing said bars from rebounding accidentally.

This compensating shock of course has a maximum intensity, and thereforea maximum efficiency, if the weights have truly started from their*rearmost positions, where they tend to be kept, as long as slide bars 6are moving frontwardly, by the combined actions of their inertia and ofreturn springs 12.

The object of the present invention is to reinforce this combined actionand to remedy any possible breakdown of springs 12.

For this purpose, sliding weights '11 and breech casing 2 are caused tocooperate frictionally so as to develop substantial friction forces atleast during the end of the frontward movement of slide bars 6.

These frictional forces will tend to keep weights 11 in their rearmostposition and possibly to return them to this position if they hadaccidentally departed therefrom.

Friction may be developed between the system of weights 1'1 and thebreech casing by rubbing elements such as elastic plates carried by oneand sliding against the other.

However, preferably, the desired frictional effect is obtained byplacing in direct contact with each other the adjacent faces of breechcasing 2 on the one hand, and sliding weights 11 on the other hand.

In order to reinforce the pressure of application of the areas incontact, each weight may be divided over at least a portion of itslength, into two portions between which elastic means are interposed tourge said portions away from each other and therefore press one of themagainst the breech casing.

However, it seems preferable, and anyway simpler, to make weights 11 ofa single piece and to mount them on slide bars 6 in such manner that,when a slide bar tends to move toward the adjacent wall of the breechcasing, the corresponding weig'htis wedged between said slide bar andsaid casing and therefore applied against the casing wall which tends byfriction to keep the Weight in rearmost position. This wedging action iscaused by the supplementary displacement of slide bars 6 engaginglocking member 5 referred to hereinbefore.

According to the embodiment illustrated by the drawing, each weight 11is constituted by a piece of general parallellepipedic shape, of lowermass than slide bar 6 but of slightly larger width, and is housed in anotch 6b provided for this purpose in the upper edge of said slide bar6.

Weight 11 is preferably made of a height equal to the depth of thisnotch whereby, in the notched portion of the slide bar (which portionextends for instance from front abutment 14 to the rear of said slidebar) the weight bears against breech casing 2 both through its externalside face 11a and through its upper face 11b.

Means are provided for reciprocally guiding weight 11 and slide bar 6,which means may be constituted by a sliding mortise and tenon assemblyas clearly shown by Fig. 2.

Advantageously, the rear abutment 13 is given a downward and rearwardinclination, whereby the combined 4 action of spring 12 and saidabutment 13 keeps weight 11 applied against slide 'b'arfi when said bar-is extracted from the firearm.

It should be pointed out that friction between the sliding weights andthe breech-casing according to the invention may be limited, if sodesired, to certain zones of the path of travel of the weights wherethis effect is most important, in particular to the zone correspondingto the end of the fron'tward stroke of the slide bars.

It will sufiice for this purpose locally to arrange the guiding faces ofthe breach casing. so that contact between the friction cooperatingparts ceases in the other zones, which is advantageous, in particular,for the zone corresponding to the frontward movement of the massesalone, which movement should not be braked.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and efficient embodiments of my invention,it should be well understood that I do not Wish to be limited thereto asthere might be changes made in the arrangement, disposition and form ofthe parts Without departing from the principle of the present inventionas comprehended within the scope of the accompanying claim.

What I claim is:

An automatic loading firearm which comprises, in combination, a breechcasing having a longitudinal wall and a notched part opposite said wall,a breech block slidable longitudinally in said breech casing, a lockingmember connected to said breech block for longitudinal movementtherewith, said locking member being movable away from said breech blockto engage said notched part to lock said breech block in the front limitposition thereof with respect to the breech casing, at least one slidebar having a portion thereof located between said locking member andsaid longitudinal wall, means mounting said slide bar on said breechblock for longitudinal movement thereof with respect to the breechblock, said means permitting transverse movement of said portion of theslide bar with respect to the breech block, at least one sliding weightdirectly interposed between the longitudinal wall and the slide bar,guide means mounting the sliding weight on the slide bar forlongitudinal movement with respect thereto, a rearward abutment on the'slide bar adapted to cooperate with the weight when the latter is moved-front Wardly with respect to said slide bar, the contacting surfaces ofthe slide bar and locking member forming camming means causingtransverse movement of the locking member toward the notched part and ofthe slide bar and the sliding weight toward the longitudinal wall of thebreech casing, said transverse movement causing frictional engagement ofthe sliding weight with the longitudinal wall to maintain said slidingweight in the rear most position thereof on the breech block until thelocking member is disposed within the notched part.

References Cited in the file of this patent UNITED STATES PATENTS2,361,985 Birkigt Nov. 7, 19'44

